Researchers from Barracuda Advanced Technology Group have spotted what they are calling an ‘aggressive' ransomware threat that appears to originate from primarily from Vietnam.

As of September 19, researchers had seen 27 million distribution attacks in just 24 hours. In later updates, the company identified it as a variant of the notorious Locky ransomware.

The ransomware is hidden in an email appearing to be from ‘Herbalife Nutrition' or in a generic email that looks like a ‘copier' file delivery, researchers say. All use fake source email addresses.

While Vietnam is the biggest attack source, other major sources include India, Columbia, Turkey and Greece.

Researchers say that there are 6000 fingerprints, which suggests that the email are automatically distributed through a template that randomizes files.

The Locky variant uses a single identifier, which allows attackers to match victims against their ransom payments. The problem is that all victims get the same identifier, making it impossible for attackers to provide the right decryptor. In which case, there may be no way for victims to get files back.

Researchers also say the attack also analyses the victim's computer language files, suggesting that it may lead to a global attack in future.

“The attack is continuing at the same pace as it has been throughout the campaign,” researchers note.

In an update on September 21, researchers noticed two new methods of attack and were spotting more than one million attacks per hour.

“The first impersonates a voicemail message, using the subject line 'New voice message [phone number] in mailbox [phone number] from ['phone number'] [<alt phone number>].'   At this time the domain in the body of the email is not returning suspicious activity. The bulk of this attack originated in Serbia,” researchers state.

They also noted that another method included a spoofed domain from marketplace.amazon.uk.

The company is keeping an eye on the attacks.